In reply to Stephen Reid:
This problem seems to go in phases - probably because the culprits eventually get nicked and put away for a bit.
A few years ago there was a spate of car break ins at the end of the lane where you walk into Cwn Silyn. I remember the ground been covered with broken windscreen glass which was so off putting that we drove back to the village and parked there, even though it meant a much longer walk in.
About the same time, it must be 5 years ago, it became a major problem at Font. Two of my mates had cars broken into. There were gangs operating out of Paris who would pull into a car park with a van, smash the windows of all the cars, sweep the contents into a bin bag and drive off. It took them about 2 mins, and even with car alarms going off, they were gone before climbers on the boulders could re-act. I heard that the French police were clamping down heavily at the time (the theives were also targeting visiting British cars in Commonwealth War Graves car parks in the Somme area). So far as I know the Font problem has subsided but not gone away completely. Any UKCers in France know?
Several decades ago it became a serious problem in the Brecon Beacons. Eventually a group got fed up with it and set a trap by leaving a car full of gear on show parked in a remote car park. They all hid in the woods and sure enough a Transit van driven by 2 didicoys arrived and tried to break in. My mates rushed out, caught them and beat the sh*t out of them, before taking them to the Police station where they explained away the thieves sorry state saying that they had "resisted arrest". The breaks in ceased.
